Final answer:
The freezing point of a 0.765 m solution of nitrobenzene in naphthalene is calculated using the freezing point depression constant (Kf) and the molality of the solution. The change in freezing point is found to be 5.69925° C, which is subtracted from the pure freezing point of naphthalene to obtain 74.6° C as the final freezing point of the solution.
Step-by-step explanation:
To determine the freezing point of a solution, you can use the formula for the freezing point depression (ΔTf), which states that ΔTf = Kf * m, where Kf is the freezing point depression constant for the solvent and m is the molality of the solution. In this case, the given Kf for naphthalene is 7.45° C kg/mol, and the molality (m) of the nitrobenzene solution is 0.765 m (which means 0.765 moles of nitrobenzene per kilogram of naphthalene).
The change in freezing point can be calculated as:
ΔTf = Kf * m
ΔTf = 7.45° C kg/mol * 0.765 mol/kg
ΔTf = 5.69925° C
After calculating the change in freezing point, subtract this value from the pure freezing point of naphthalene (Pure freezing point = 80.3° C) to find the freezing point of the solution:
Freezing point of the solution = Pure freezing point - ΔTf
Freezing point of the solution = 80.3° C - 5.69925° C
Freezing point of the solution = 74.60075° C (rounded to 74.6° C)